<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>左栏</title>
		<style>
			div{
				width: 300px;
				height: 300px;
			}
			div.taiyi{
				background: url(img/1.png);
				background-size: 100% 100%;
				position: absolute;
				z-index: 999;
			}
			div.shengongbao{
				background: url(img/4.png);
				background-size: 100% 100%;
				position: absolute;
				z-index: 1000;
			}
		</style>
	</head>
	<body>
		<article>
			<ul class="sidebar">
				<div class="outer"></div>
				<li>lorem1</li>
				<li>lorem2</li>
				<li>lorem3</li>
				<li>lorem4</li>
				<li>lorem5</li>
				<li>lorem6</li>
				<li>lorem7</li>
				<li>lorem8</li>
				<li>lorem9</li>
				<li>lorem10</li>
			</ul>
		</article>
		
		
		
		
		
		<d iv class="taiyi"></div>
		<d iv class="shengongbao"></div>
	</body>
</html>